Alloy composition



, Patented Dec. 8, 1931 PATENT OFFICE .MICHAEL GEORGE GORSON, OF JACKSON HEIGHTS; NEW YORK ALLOY COMPOSITION No Drawing;

This invention relates to an alloy composition, which is particularly suitable for the manufacture of small parts of precision machinery and instruments and also of ornamental articles by the process of diecasting.

However, while the usual diecasting compositions belong to the groups of zinc, or tin or aluminum, base alloys,-the subject of the present invention is a silver base alloy, which A in its mechanical properties closely approaches bronzes, but is of a'pleasant silvery color, lesser specific density (from 54 to 6 2) vand resists tarnishing to a considerable degree, especially when chill cast or die-cast.

This alloy composition consists mainly of silver and aluminum, the first me al forming from 65 to 80 per cent by Weight and the second practically completes the composition to 100 per cent. So while such metals as got-.admium, tin, zinc. antimony, copper magnesium and lead may be present incidentally, or even incorporated on purpose in the composition, their content-shall not exceed 2%.' For chill castings-the alloy shall preferper cent of aluminum, While fordie-ca'sting and sand casting, also for Wrought metal articles about 77 per cent of silver is desirable. Th'ereasdn for this difference lies in the observation, that structurally these twotypes of composition will look alike. In the chill cast state much more of the compound Ag Al will crystallize primarily in the shape of large individual grainlets, than in the sand cast state for the same composition and the structures can bemade almost identical only by lessening the silver content for chillcast- The uniform distribution of these indi- 40 -vidual grainlets of Ag Al within a grid shaped euteetic'ground mass makes the alloys of the present invention analogous to bronzes with their islands of delta constituent ,and to lead-tin-antiniony alloys where a t'm-antimony compou nd SbSn forms primary crystals within a eutectic ground mass.

Thisspecific structure of the alloys here described makes them suitable for the manufacture of small gears, bushings and the like. They are especially convenient for this purablycontain 72 per cent of silver and '26-28 F I Application filed February 17, 1931. Serial No. 516,513.

pose due to their ability to acquire when cast in a permanent mold a smooth velvety surface.

While the alloys here described are especially intended for die casting, they can be used in a number of forms. They can be hammered, forged and rolled to a considerable degreeiand articles in-these compositions can be obtained by working the alloys first into sheets, or extruding them into rods '60 and applying to such semi-products any known process of final shaping.

Having so described my invention, I wish to claim a An alloy composition consisting mainly of silverand aluminum the amount of the first being from to per cent and of the second from 20 to 35 per cent.

Signed" at 3436 76th .Street; Jackson Heights, in thecounty ofQueens and State of New York, this 11th day of February A. 1931; v

' MICHAEL GEORGE CORSON. 

